1. Field of the Invention
The present invention relates to a print head for discharging ink.
2. Description of the Related Art
In a configuration of a print head of a printing apparatus, a technique is widely used in which nozzles (recording devices) that perform discharge are divided into groups, thereby reducing ampacity. Generally, electric heat converters necessary for discharging ink from a print head and switching elements for driving the electric heat converters are formed on the same element substrate. Heater selecting circuits for selecting a switching element, shift registers and decoders are also provided on such an element substrate. The shift register is used for holding a group selection signal for selecting an arbitrary group from a plurality of groups, and the decoder is used for selecting an arbitrary nozzle from among a plurality of nozzles. A typical configuration on the element substrate is such that a supply opening for introducing ink from a back face of the substrate to a front face is disposed at the center of the substrate, and heaters, switching elements, and heater selecting circuits are arranged around the supply opening. Accordingly, with such a configuration, the shift registers, the decoders or the like are arranged in an end portion on the substrate together with pads arranged in the end portion for receiving input from signal lines.
However, as the number of nozzle groups increases, the number of output signals from the shift registers also increases. As a result, the circuit size of the shift register increases, and moreover, the substrate size also increases due to the area occupied by wirings corresponding to the increased number of output signals.
Japanese Patent Laid-Open No. 2005-199703 discloses a substrate in which one-bit shift registers are arranged distributed in the vicinity of the respective nozzle groups. The configuration disclosed in Japanese Patent Laid-Open No. 2005-199703 suppresses an increase in the circuit size of the shift register, and also is considered to be effective in suppressing an increase in the substrate size due to the area occupied by wirings corresponding to the number of output signals.
In addition, Japanese Patent Laid-Open No. 2005-199703 discloses a configuration in which not only the shift registers, but also logic elements included in the decoder are also arranged distributed in the vicinity of the respective nozzle groups. With such a configuration, it is considered to be possible to suppress further increase in the substrate size. However, since two types of signal lines for an inverse signal and a non-inverse signal of a logical value are wired from the substrate end portion to the decoder, the area occupied by these wirings will be large.